This invention relates to a machine for forming cylindrical bales of crop material, such as hay and the like, and more particularly to an improved machine of the above general type wherein the bale is formed off the ground. A machine of the above general type is shown in U.S. Pat. No. 3,931,702, which is also assigned to the assignee of the present application. In the machine described in said patent, the bale is supported from below on a lower conveyor during its entire formation, the bale being formed between the rearwardly moving upper run of the lower conveyor and the forwardly moving lower run of an upper conveyor. The upper conveyor includes a lower rear roller about which a plurality of side by side belts are trained, said roller being mounted on a rear gate assembly that swings rearwardly and upwardly so that the roller clears a fully formed bale to permit rearward discharge of the bale from the machine.
To reduce the cost of the machine, such balers have been provided with much shorter lower conveyors, wherein the rearward end of the lower conveyor is generally below the center of a fully formed bale, the lower rear roller that is mounted on the rear gate assembly of such machines being disposed immediately to the rear of the rearward end of the lower conveyor, thereby substantially supporting the weight of the bale after it reaches a certain size. In certain machines of the above general type, the lower conveyor is formed by a series of rollers, such as schematically shown in U.S. Pat. No. 3,992,987, while in other machines the lower conveyor is formed by a belt trained around a number of rollers, although in both cases, the weight of the bale is supported on the lower rear roller of the upper conveyor after the initial stages of the bale formation.
Typically, the diameter of the lower rear roller is about four inches, and the relatively small diameter of the roller as compared to the diameter of the fully formed bale, which approximates six foot in diameter, causes a penetration or depression in the periphery of the bale at the point of engagement with the roller. This deformation of the roll periphery travels around the periphery as the bale rotates and creates a significant resistance to the rolling of the bale. The resistance to rolling, of course, requires power to overcome, and the more power necessary to rotate the bale the greater the amount of tension in the belts of the upper conveyor, which engage the bale and turn the bale. Since the density of the bale is affected by the tension in the belts of the upper conveyor, which substantially envelop the bale, the increased belt tension and rolling resistance due to the penetration of the bale by the lower rear support roller have increased the bale density as well as significantly increasing the power required to operate the baler. While in some crop materials, such as lighter and dryer grasses, the rolling resistance created by the roller penetration have in fact been advantageous since it increased the bale density, in more dense crop materials, such as alfalfa having a higher moisture content, the rolling resistance due to the penetration of the bale has raised the power requirement and bale density to undesirable levels, the tension of the belts in some cases reaching a level wherein belt damage or fracture occurs.